With the rapid development of the electric information industry, and the promotion of market demands and advances, the capacity of the information transmission has been increased, requiring high-speed signal transmission and treatment. The traditional 2D integration technologies may lead to signal distortion and delay. Therefore, 3D integration technologies are used to reduce wiring, realize multi-layer integration, improve performance and reduce power consumption. During the utilization of the 3D technologies, Through Silicon Via (TSV) technology has played an important role, which could make the 3D interconnection come true.
TSV manufacturing technologies mainly include: formation of through holes; depositions of the insulating layer, barrier layer and seed layer; and the electroplating and removal of the through holes and the electroplating of the re-distribution lead (RDL). During the electroplating of the through holes, two method could be used, namely, conformal plating and super-conformal plating which is also called bottom-up plating, as shown in FIG. 1 and FIG. 2 respectively.
The bottom-up plating has the following characteristics in terms of hole filling compared with the conformal plating: the development in the blind hole is started from the bottom directly in the U-shape, and there is only a very thin plating layer on the whole wall, which may improve the electroplating speed to the maximum extent. Micro-voids could be found between the grain boundaries in the TSV copper column for the bottom-up plating after the annealing due to the development pattern and the piling pattern during the copper deposition, which may influence the confidence. Therefore, an electroplating additive or process is needed to eliminate the micro-voids between grain boundaries after the annealing of the TSV electroplating.
Annealing process is a heat treatment process for metal, which is to heat the metal to certain temperature slowly, maintain the temperature for a while and then cool the metal at the appropriate speed. The purpose of the annealing is to reduce the hardness and improve machinability; eliminate residual stress, stabilize sizes and reduce deformation and cracks; and refine grains, adjustment organization and eliminate organization flaws. However, during the bottom-up electroplating copper annealing, while the Cu grain is developing and integrating, micro-voids may develop between different grains.